GABA-A Alpha-5 Protein — GABA-A Receptor Alpha 5 Subunit

GABA-A Alpha-5 Protein

<table class="infobox infobox-protein">
<tr>
<th class="infobox-header" colspan="2">GABA-A Alpha-5 Protein — GABA-A Receptor Alpha 5 Subunit</th>
</tr>
<tr>
<td class="label">Symbol</td>
<td><strong>GABRA5</strong></td>
</tr>
<tr>
<td class="label">Full Name</td>
<td>GABA-A Alpha-5 — GABA-A Receptor Alpha 5 Subunit</td>
</tr>
<tr>
<td class="label">Type</td>
<td>Protein</td>
</tr>
<tr>
<td class="label">UniProt</td>
<td><a href="https://www.uniprot.org/uniprot/?query=GABRA5" target="_blank">Search UniProt</a></td>
</tr>
<tr>
<td class="label">Associated Diseases</td>
<td><a href="/wiki/als" style="color:#ef9a9a">ALS</a>, <a href="/wiki/als" style="color:#ef9a9a">Als</a>, <a href="/wiki/bipolar" style="color:#ef9a9a">Bipolar</a>, <a href="/wiki/depression" style="color:#ef9a9a">Depression</a>, <a href="/wiki/ms" style="color:#ef9a9a">Ms</a></td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">57 edges</a></td>
</tr>
</table>

Introduction

Gaba A Alpha 5 Protein — Gaba A Receptor Alpha 5 Subunit is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.

Overview

...

GABA-A Alpha-5 Protein

<table class="infobox infobox-protein">
<tr>
<th class="infobox-header" colspan="2">GABA-A Alpha-5 Protein — GABA-A Receptor Alpha 5 Subunit</th>
</tr>
<tr>
<td class="label">Symbol</td>
<td><strong>GABRA5</strong></td>
</tr>
<tr>
<td class="label">Full Name</td>
<td>GABA-A Alpha-5 — GABA-A Receptor Alpha 5 Subunit</td>
</tr>
<tr>
<td class="label">Type</td>
<td>Protein</td>
</tr>
<tr>
<td class="label">UniProt</td>
<td><a href="https://www.uniprot.org/uniprot/?query=GABRA5" target="_blank">Search UniProt</a></td>
</tr>
<tr>
<td class="label">Associated Diseases</td>
<td><a href="/wiki/als" style="color:#ef9a9a">ALS</a>, <a href="/wiki/als" style="color:#ef9a9a">Als</a>, <a href="/wiki/bipolar" style="color:#ef9a9a">Bipolar</a>, <a href="/wiki/depression" style="color:#ef9a9a">Depression</a>, <a href="/wiki/ms" style="color:#ef9a9a">Ms</a></td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">57 edges</a></td>
</tr>
</table>

Introduction

Gaba A Alpha 5 Protein — Gaba A Receptor Alpha 5 Subunit is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.

Overview

GABRA5 is a subunit of the GABA-A receptor, a ligand-gated chloride channel that mediates inhibitory neurotransmission in the central nervous system. The alpha-5 subunit is encoded by the GABRA5 gene located on chromosome 15q12 and is predominantly expressed in the hippocampus and [cortex](/brain-regions/cortex). GABA-A receptors containing the alpha-5 subunit are extrasynaptic and mediate tonic inhibition, which is important for memory processes, spatial navigation, and emotional regulation. These receptors are implicated in cognitive disorders and are targets for cognitive enhancement and anxiolytic drugs.

Structure

GABRA5 contains:

• Extracellular N-terminal domain: Contains the benzodiazepine binding site
• Transmembrane domains: Four transmembrane helices forming the channel pore
• Intracellular loop: Contains sites for phosphorylation
• C-terminal domain: Important for receptor clustering

Molecular Function

Tonic Inhibition

GABRA5-containing GABA-A receptors mediate tonic inhibition:

Extrasynaptic location: High affinity for GABA allows activation by ambient GABA

Sustained chloride current: Provides persistent hyperpolarization

Dendritic integration: Modulates dendritic excitability

Network oscillations: Regulates hippocampal rhythm generation

Pharmacological Properties

• Benzodiazepine sensitivity: High sensitivity to inverse agonists
• Neurosteroid modulation: Modulated by endogenous neurosteroids
• Ethanol sensitivity: Involved in ethanol's cognitive effects

Expression Pattern

GABRA5 is expressed in:

• [Hippocampus](/brain-regions/hippocampus) (high expression in CA1-CA3)
• Cerebral cortex (layers II-V)
• Basal ganglia
• [Cerebellum](/brain-regions/cerebellum)

Disease Associations

Alzheimer's Disease

• Memory impairment associated with alpha-5 changes
• GABAergic dysfunction in AD
• Inverse agonists may improve cognition

Down Syndrome

• GABRA5 located on chromosome 21
• Triplication contributes to cognitive deficits
• Therapeutic target

Epilepsy

• Altered expression in epileptic tissue
• Contributing to network hyperexcitability

Therapeutic Implications

Drug Targets

Inverse agonists: Enhance cognition (e.g., L-838417)

Positive allosteric modulators: Memory enhancement

Selective compounds: Fewer side effects

See Also

• [GABRA5 Gene](/proteins/gabra5-protein)
• [GABA-A Receptor](/proteins/gaba-a-receptor)
• [Inhibitory Neurotransmission](/mechanisms/gaba-signaling)

Background

The study of Gaba A Alpha 5 Protein — Gaba A Receptor Alpha 5 Subunit has evolved significantly over the past decades. Research in this area has revealed important insights into the underlying mechanisms of neurodegeneration and continues to drive therapeutic development.

Historical context and key discoveries in this field have shaped our current understanding and will continue to guide future research directions.

External Links

• [PubMed](https://pubmed.ncbi.nlm.nih.gov/) - Biomedical literature
• [Alzheimer's Disease Neuroimaging Initiative](https://adni.loni.usc.edu/) - Research data
• [Allen Brain Atlas](https://brain-map.org/) - Brain gene expression data

Molecular Mechanisms

The GABA-A Alpha-5 subunit (GABRA5) is enriched in the hippocampus, particularly in the CA1 region and dentate gyrus, where it contributes to hippocampal inhibitory circuits. Alpha-5 containing GABA-A receptors are primarily extrasynaptic, responding to low concentrations of GABA to generate tonic inhibition.

These receptors play a critical role in hippocampal memory circuits, modulating synaptic plasticity and network oscillations. The Alpha-5 subunit is also expressed in the cortex and olfactory bulb, contributing to sensory processing.

Disease Associations

Alzheimer's Disease: GABRA5 expression is altered in AD, affecting hippocampal inhibitory tone. Alpha-5 receptors may be involved in the memory deficits characteristic of AD, as they play important roles in hippocampal plasticity. Some studies suggest these receptors could be therapeutic targets.

Parkinson's Disease: Alpha-5 receptors may contribute to cognitive dysfunction in PD, as the hippocampus is affected in PD-related dementia. The subunit's role in spatial memory is particularly relevant.

Huntington's Disease: GABRA5 expression is altered in HD, contributing to the characteristic motor and cognitive symptoms. The receptor may be a therapeutic target.

Therapeutic Implications

Inverse agonists at GABA-A Alpha-5 receptors have been explored for cognitive enhancement, as they increase hippocampal excitability and may improve memory formation. However, these compounds have shown limited efficacy and safety concerns in clinical trials.

Research Directions

Research focuses on understanding the role of Alpha-5 receptors in memory formation and developing safe modulators for cognitive enhancement.

References

Möhler et al, (2002) Nat Rev Neurosci 3:413-425 (2002)

Unknown, Atack (2011) Adv Pharmacol 59:53-92 (2011)